Functional Testing awesomeness with Webrat

August 09, 2008 by alex

I recently started using Webrat in one of our project’s test suites and fell in love with it immediately. Webrat is a functional testing library for Ruby on Rails which you can use in your rails integration tests (or better: the RSpec Story Runner) to let your tests walk through your application. The big difference between Webrat and a “standard” Rails Integration Test is that with Webrat you click on actual links and submit actual forms, instead of just sending requests to you application.

This closes an important gap to testing in a real browser (like with Selenium) and now gives us much more confidence in our tests - we now not only know that our models and controllers integrate, but we also know that they work with our views. That had been an unpleasant problem for a while. All our tests were passing but we still had way too many problems with invalid links and forms submiting to the wrong action. No more.

Webrat provides a sort of DSL (everything is a DSL nowaday isn’t it? :) ) for interacting with all the HTML elements you would find in a HTML document like links, checkboxes, radio buttons, text fields, selects and submit buttons. A test case might look like this:

visits '/'
clicks_link 'Sign up'
fills_in 'username', :with => 'joedoe'
selects 'Male'
checks 'Terms of Service'
clicks_button

Webrat now fetches the start page of the application, parses it and follows the first link labelled with “Sign Up”, gets the corresponding page, parses the form, fills in the values and submits it. Whenever a response comes back with anything else than a 200 (or 302, in which case that redirection is followed automatically) or an element on the page can’t be found, Webrat complains with an error and you know there’s probably something wrong in your view.

In Order to get this working with Story Runner I have wrapped most calls into When calls, for example:

When 'I click on $link' do |link|
  clicks_link link
end
When 'I submit the form' do
  clicks_button
end
When 'I select $option' do |option|
  selects option
end

And now my Story looks like this:

Scenario: successful signup
  When I go to the start page
  And I click on Sign up
  And I select Male
  And I check the Terms of Service
  And I submit the form
  Then the page should show Thank you for signing up

I’m not sure yet if it makes sense to release those wrappers as a plugin, we’ll see. After all it’s just a few lines of trivial code.

By the way, Webrat is hosted on awesome github, so after using it for 30 minutes (seriously) I forked my own version and added support for the Rails date helpers (selects_date Date.today, :from => 'signup_date' instead of selects 'December', :from => 'signup_date_2i'; selects '2008', :from => 'signup_date_1i'; selects '01', :from => 'signup_date_3i') and Emails (e.g. clicking the activation link in a signup email). (Bryan Helmkamp, if you read this: Why haven’t you pulled this (and in fact any other fork) into the main line yet?)

All in all the experience has been fantastic. Webrat is on all my Rails projects now. The only - conceptual - problem so far is that I can’t use it to test AJAX. But that’s the topic of another post. And there’s a fork on github that experiments with celerity, which can do AJAX and everything.

This entry was posted on August 09, 2008 by alex.